Comparison of novel risk markers for improvement in cardiovascular risk assessment in intermediate-risk individuals

Abstract

Context: Risk markers including coronary artery calcium, carotid intima-media thickness, ankle-brachial index, brachial flow-mediated dilation, high-sensitivity C-reactive protein (CRP), and family history of coronary heart disease (CHD) have been reported to improve on the Framingham Risk Score (FRS) for prediction of CHD, but there are no direct comparisons of these markers for risk prediction in a single cohort.

Objective: We compared improvement in prediction of incident CHD/cardiovascular disease (CVD) of these 6 risk markers within intermediate-risk participants (FRS >5%-<20%) in the Multi-Ethnic Study of Atherosclerosis (MESA).

Design, setting, and participants: Of 6814 MESA participants from 6 US field centers, 1330 were intermediate risk, without diabetes mellitus, and had complete data on all 6 markers. Recruitment spanned July 2000 to September 2002, with follow-up through May 2011. Probability-weighted Cox proportional hazard models were used to estimate hazard ratios (HRs). Area under the receiver operator characteristic curve (AUC) and net reclassification improvement were used to compare incremental contributions of each marker when added to the FRS, plus race/ethnicity.

Main outcome measures: Incident CHD defined as myocardial infarction, angina followed by revascularization, resuscitated cardiac arrest, or CHD death. Incident CVD additionally included stroke or CVD death.

Results: After 7.6-year median follow-up (IQR, 7.3-7.8), 94 CHD and 123 CVD events occurred. Coronary artery calcium, ankle-brachial index, high-sensitivity CRP, and family history were independently associated with incident CHD in multivariable analyses (HR, 2.60 [95% CI, 1.94-3.50]; HR, 0.79 [95% CI, 0.66-0.95]; HR, 1.28 [95% CI, 1.00-1.64]; and HR, 2.18 [95% CI, 1.38-3.42], respectively). Carotid intima-media thickness and brachial flow-mediated dilation were not associated with incident CHD in multivariable analyses (HR, 1.17 [95% CI, 0.95-1.45] and HR, 0.95 [95% CI, 0.78-1.14]). Although addition of the markers individually to the FRS plus race/ethnicity improved AUC, coronary artery calcium afforded the highest increment (0.623 vs 0.784), while brachial flow-mediated dilation had the least (0.623 vs 0.639). For incident CHD, the net reclassification improvement with coronary artery calcium was 0.659, brachial flow-mediated dilation was 0.024, ankle-brachial index was 0.036, carotid intima-media thickness was 0.102, family history was 0.160 and high-sensitivity CRP was 0.079. Similar results were obtained for incident CVD.

Conclusions: Coronary artery calcium, ankle-brachial index, high-sensitivity CRP, and family history were independent predictors of incident CHD/CVD in intermediate-risk individuals. Coronary artery calcium provided superior discrimination and risk reclassification compared with other risk markers.

Figure 1

A: Receiver operator characteristic curves showing the area under the curve (AUC)for FRS, FRS + CAC , FRS + FMD , FRS +ABI, FRS + IMT, FRS + FH and FRS + CRP for incident CHD in MESA Intermediate Risk Participants . * denotes reference. CAC-coronary calcium score, FMD- flow mediated dilation, IMT- intima-media thickness, ABI- ankle brachial index, hs-CRP- high sensitivity C - reactive protein.

Figure 2

B: Receiver operator characteristic curves showing the area under the curve for FRS, FRS + CAC, FRS + FMD, FRS +ABI, FRS + IMT, FRS + FH and FRS + CRP for incident CVD in MESA Intermediate Risk Participants . * denotes reference. CAC- coronary calcium score, FMD- flow mediated dilation, IMT- intima-media thickness, ABI- ankle brachial index, hs-CRP- high sensitivity C - reactive protein.